Vapor stream vacuum pump



Mamh 28, W50 J. w. THLL$ 2,501,923

VAPOR STREAM VACUUM PUMP Filed Feb. 22, 1945 4 Sheets-Sheet l k Inventor Attorneys March 28, 1950 4 Sheets-Sheet 2 Filed Feb. 22, 1945 r m A inventor wmw March 28, 1950 Filed Feb. 22, 1945 J. W. TILLS VAPOR STREAM VACUUM PUMP 4 Sheets-Sheet 3 March 28, 1950 J. w. TlLLS VAPOR STREAM VACUUM PUMP Filed Feb. 22, 1945 4 Sheets-Sheet 4 (7) Ego Inventar Patented Mar. 28, 1950 VAPOR STREAM VACUUM PUMP John W. Tills, Upton, England Application February 22, 1945, Serial No. 579,178 In Great Britain February 23, 1944 12 Claims. 1

This invention relates to vapour stream vacuum pumps. I

One object is to increase pumping speed.

Another object is to provide a pump which will operate against higher forevacuum pressures than have been usual heretofore.

A further object is to achieve greater reliability of operation with longer intervals between changes or replenishments of working fluid in the system.

Yet a further object is the provision of a pump of robust and durable construction especially suitable for many industrial purposes. These and other objects will be apparent from the following description of, by Way of'example, one preferred form of construction illustrated in the drawing annexed hereunto.

In the drawings: Fig. 1 is a side elevation, partly in section, showing a vessel and ancillary parts for working fluid supply and storage; Fig. 2

is a fragmentary detail section, partly in elevation, showing the construction of the vapour stream pump in its relation to the vessel and ancillary parts of Fig. 1; Fig. 3 is a general arrangement in side elevation showing the apparatus complete with backing pump; Fig. 4 is a vertical section of an alternative construction.

A substantially gas-tight steel vessel has a lid H gas-tightly secured thereto. An electric motor I2 mounted on a lid ll drives, by way of a belt I3, a spindle M of a stufling box assembly secured to the wall of vessel I0 so as to partially project therethrough. Spindle M is connected through a coupling [5, preferably flexible to a multicylinder piston pump l6. Pump [5 is fed by an inlet pipe I! and discharges through pipe [8 to a blow-oil or pressure release valve assembly I9 supported from the wall of vessel I0 and having an adjustment spindle 20 passing through a stuffing box to atmosphere and terminating in a handwheel 2 I. A pipe 22 extends between valve assembly l9 and a flange 23 to which it is secured by welding or brazing. Flange 23 is bolted or otherwise secured to the inner side of a pad 24 built into and extending through a wall of vessel 10. A flange 25 to which is attached an end of a pipe 26, is secured to the outside of pad 24. Pipe 26 is connectable by a valve 21 to a pressure gauge 28. A'pipe 29 is connectable to a branch of p'ipe26 by a valve 30.

Pipe 29 leads from valve 30 to an outer wall 31- of a cooling jacket surrounding a cone shaped body- 32 of a vapour stream pump.

4 One end of a helical conduit 33, which may be of stainless steel, extends through wall of body 32 into the cooling jacket, is supported from the said wall and makes electrical contact thereside of which'is grounded to the vessel and thence to the pump body 32. A mechanical backing pump 38, driven by an electric motor 39 has its inlet connected by a 'forevacuum conduit 40 to a vertical forevacuum chamber 4| mounted substantially gas-tightly on lid II. The small diameter end of the pump body 32 is connected obliquely to, as a side arm in the wall of chamber 4| A semiflexible electrical conductor 42, suitably insulated from the inner surfaces of body 32 and chamber 4| extends between so as to connect the ungrounded end of winding 31 with the end of helix 33 near nozzle assembly 34.

In operation a working fluid such as dibutyl phthalate is introduced into vessel l0 so as to cover the coils 36, 31 of the transformer.

The backing pump 38 is started up' and after a suitable forevacuum has been attained within vessel It], chamber 4| and pump body 32, pump I6 is started up. Valve l9 may be adjusted until, with valves 21 and 30 open, a desired liquid pressure obtains in pipe 29, as indicated on gauge 28. 5 to 50 lbs/square inch is a convenient range from which to select a working pressure. Liquid will now be emitted by nozzle assembly 34 which-liquid will return by gravity to vessel H1 and eventually will be recirculated through pump I6. An inspection window (not shown) may be provided in the wall of vessel ID for observation of returning liquid.

Finally the primary winding 36 of the transformer may be energised, causing a heavy secondary current to flow through and heat conduit 33.

Conduit 33 then acts as a flash boiler and discharges vapourized working fluid to nozzle assembly 34. Vapour stream pumping action is then initiated, producing a high vacuum in any suitable closed system which may be connected to flange 35.

-Vapourised pumping fluid eventually condenses onthe inner surface of body 32 and the condensate returns by gravity to vessel Ill. The working fluid passing through the jacket under pressure from pipe 29 effectively maintains the jacket at a sufliciently low temperature for efficient condensing action and is itself preheated prior to passing into the flash boiler constituted by conduit 33.

The boiler may of course supply more than one jet disposed in cascade or parallel.

The nozzle assembly preferably exerts a restrictive action on the vapour to maintain pressure in the boiler.

In an alternative embodiment of the invention (Fig. 4), a flash boiler has a vertical cylindrical copper body 581 doubly flared at its .lowerend forming a nozzle 5| of conical annular .form. Projecting from annular nozzle'5l arepassageways 52 communicating with a central cavity 53 formed as a lower portion of an axialzboreinthe body 50. This bore extends for approximately half the height of the body, for the remainder .of which height it is counterboredto-receivealoose cup 54. One or more passageways ".49 provide .communication between cavity 53 and cup 54. In :the base of cup 54 a valve seating 55 is formed :coaxial with body 50.

A ,valve head formed at the upper end of a needle valve-spindle 56 coacts with seating 55.

..A bobbin-shaped member 5'! has alower flange 4 excess liquid passing out from cooling chamber 66 through conduit 68 is collected and eventually recirculated and fed into conduit 61 for further action in the manner described.

I claim:

1. A high vacuum pump adapted to evacuate closed systems to low absolute pressures comprising in combination a closed chamber having .an inletfor gases to' be entrained, a vapour 1O stream nozzle located near one end of the chamber and directed towards the opposite end of the chamber, means for cooling at least part of the wallsof said chamber, a collecting and separating means for liquid and entrained gases at the end of :the chamber opposite to the nozzle, said collecting and separating means containing a low vapour pressure organic liquid, an electrically heated flash boiler for heating and vapourising collectedliquid, means for compressing such collected liquid, means for conveying compressed liquid to the flash boiler, means for conveying heated and vapourised liquid from said flash boiler to said nozzle, and an exhaust port .for removing the entrained gases from-the collecting or) and separating means.

.threadedly attached to the upper end of'body 55.

-..extending hollow portion 65 forming acooling chamber '66 for the valve head on spindle .56 .and complementary seating 55. Communicating with chamber 66 is a fluid inlet conduit 6-1 .arranged diametrally opposite a fluid outlet-coneduit 68. I

The assembly is suitably positioned coaxially within a cooled conical condensing body 6'9, to .the upper end of which is connected a system to 'be evacuated. -A forevacuum connection (not shown) is provided near thelower end of body 69.

In operation working fluid is supplied under .pressure by way of conduit 6-! to the spacewfifi. Thence a jet of liquid impinges on the inner; and lower surface of deflector 60, and then :passes downwardly on to the sides and bottom ofcup 54. .This cup is heated from body 50 which inturn is 'heated by spiral 62. Asuitablecurrent, zprefer- .ably high amperage at low voltage, is passed through spiral 62 from conductors B3 and to .raise the temperature of cup 54 .to a temperature sufficient to vapourise working fluid: directed into said cup. Vapour generated in cup 54 passes downwardly through passageways into cavity 53 and thence through passageways 52 issuing in ;a:stream through nozzle .51. At the same time part of the vapour passes upwardly through the lcentre of member 5'7 and issues by'way ofpassageways 48 and are deflected downwardlyin a :jetbymeans of the cowl formedbyflangeSB.

The vapours from both nozzles, afterexerting pumping. action are condensed on the sinner. surztacesof; condensingrbody' 69. The condensate and 2. A high vacuum pump adapted to evacuate closed systems to low absolute pressures comprising in combination a closed chamberhaving an inlet for gases to be entrained, a vapour stream nozzle located near one end of the chamber and directed towards the opposite end of the chamber, means for cooling-at least part-of the walls of said chamber, a collecting and separating means for liquid and entrained gases at the end of the chamber opposite to the nozzle, said .collecting and separating means containing a low vapour pressure organic liquid, an electrically heated flash boiler within the chamber for heating and vapourising collected:liquid, means -for compressing such collected liquid, means for conveying compressed liquid to the flash boiler, means for conveying heated and vapourised liquid ;from said flash boiler to said nozzle, and an exhaust port for removing the entrained gases from the collecting and separating means.

3. A high vacuum pump adapted to evacuate closed systems to low absolute pressures comprising in combination a closed chamber having an inlet for gases to be entrained, a nozzle located within the chamber and directed-towards -.oneend of the chamber, means for cooling at .least part of the walls of said chamber, a collecting and separating means for liquid and entrained gases at the said end of the chamber, said.col-

lecting and separating means containing a low vapour pressure organic liquid, an electrically .heated flash boiler for .vapourising collected v li quid, .means for compressing such collected liquid, means for conveying compressed liquid .to

n the flash boiler, means for conveying vapourised liquid from said flash boiler to said nozzle, and an exhaust port for removing the. entrainedgases from the collecting and separating means.

4. A high vacuum pump adapted to evacuate 55 closed systems to low absolute pressures com- ;prising-in combination a closed chamber having an inlet for gases to be entrained, a nozzle 10- =catednearone end of the chamberand directed :towards the opposite end of the chamber, means 470 for cooling at least part oi the walls of said pressure organic liquid, an electrically heated flash boiler for vapourising collected liquid, means for compressing such collected liquid, means, for conveying compressed liquid to the flash boiler, means for conveying vapourised liquid from said flash boiler to said nozzle, and a forevacuum connection for removing the entrained gases from the collecting and separating means,

5. A high vacuum pump adapted to evacuate closed systems to low absolute pressures comprising in combination a closed chamber having an inlet for gases to be entrained, a nozzle within the chamber, and directed towards one end of the chamber, means for cooling at least part of the walls of said chamber, a collecting and separating means for liquid and entrained gases at the end of the chamber opposite to the nozzle, said collecting and separating means containing a low vapour pressure organic liquid, an electrically heated flash boiler for vapourising collected liquid disposed within the chamber adjacent the nozzle, means for compressing such collected liquid, means for conveying compressed liquid to the flash boiler, means for conveying vapourised liquid from said flash boiler to said nozzle, and a forevacuum connection for removing the entrained gases from the collecting and separating means.

6. A high vacuum pump adapted to evacuate closed systems to low absolute pressures comprising in combination a closed chamber having an inlet for gases to be entrained, a nozzle located near one end of the chamber and directed towards the opposite end of the chamber, means for cooling at least part of the walls of said chamber, a collecting and separating means for liquid and entrained gases at the end of the chamber opposite to the nozzle, said collecting and separating means containing a low vapour pressure organic liquid, a flash boiler constituted by a coiled conduit adapted to be heated by passing a high amperage electric current therethrough for vapourising collected liquid, means for compressing such collected liquid, means for conveying compressed liquid to the flash boiler, means for conveying vapourised liquid from said flash boiler to said nozzle, and a forevacuum connection for removing the entrained gases from the collecting and separating means.

7. A high vacuum pump adapted to evacuate closed systems to low absolute pressures comprising in combination a closed chamber having an inlet for gases to be entrained, a nozzle located near one end of the chamber and directed towards the opposite end of the chamber, means for cooling at least part of the walls of said chamber, a collecting and separating means for liquid and entrained gases at the end of the chamber opposite to the nozzle, said collecting and separating means containing a low vapour pressure organic liquid, a flash boiler constituted by a conduit adapted to be heated by passage of a high amperage electric current therethrough for vapourising collected liquid, said flash boiler being disposed within said chamber, means for compressing such collected liquid, means for conveying compressed liquid to the flash boiler, means for conveying vapourised liquid from said flash boiler to said nozzle, and a forevacuum connection for removing the entrained gases from the collecting and separating means.

8. In a vapour stream vacuum pump, a pump iii) body including a chamber having walls at least partially cooled and an inlet for gases to be entrained, an electrically heated flash boiler disposed within the chamber, means for supplying acompressed organic liquid of low vapour pressure to said flash boiler, and a nozzle arranged within the chamber for emitting a vapour stream capable of entraining gases to be pumped and adapted to be supplied with vapourised working fluid from said flash boiler. I

9. In a vapour stream vacuum pump, a pump body including a chamber having walls at least partially cooled and an inlet for gases to be entrained, an electrically heated flash boiler disposed within the chamber and constituted by a conduit heated by passage of a high amperage electrical current therethrough, means for supplying a compressed organic liquid of low vapour pressure to said flash boiler, and a nozzle arranged within the chamber for emitting a vapour stream capable of entraining gases to be pumped and adapted to be supplied with vapourised working fluid from said flash boiler.

10. In a vapour stream vacuum pump a pump body including a chamber having walls at least partially cooled and an inlet for gases to be entrained, a flash boiler constituted by a metal tube having two ends, means for passing an electrical current through said tube to effect heating thereof, means for supplying a compressed organic liquid to one end of said tube, and a nozzle arranged within the chamber and connected to the other end of said tube for emitting a vapour stream capable of entraining gases to be pumped.

11. An arrangement for evacuating a vessel, comprising a high vacuum connection on said vessel, a backing pump, a conduit length extending between said backing pump and said high vacuum connection and sloping downwards towards said backing pump, a unitary flash boiler and nozzle disposed within said conduit length and directed away from said high vacuum connection, working fluid storage means, means for supplying working fluid to said unitary flash boiler and nozzle, and means for returning condensate of working fluid discharged through said nozzle to said storage means.

12. In a vapour stream vacuum pump, a pump body including a chamber having walls at least partially cooled and an inlet for gases to be entrained, a flash boiler within said chamber and constituted by a metal tube having two ends, means for passing an electrical current through said tube to effect heating thereof, means for supplying a compressed organic liquid to one end of said tube, and a nozzle arranged within the chamber and connected to the other end of said tube for emitting a vapour stream capable of entraining gases to be pumped.

JOHN W. TILLS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 743,103 Ray Nov. 3, 1903 1,053,375 Gafiney et al Feb. 18, 1913 1,674,377 Smith June 19, 1928 2,338,583 Hickman et a1 June 19, 1928 

